Light-emitting diodes (LED) have been one of the most important inventions in the history of technological advancement. As widely known, an LED is a device that is able to emit light when a forward bias (voltage) is imposed on the semiconductor PN junction. he LEDs have the advantages of low energy-consumption, low heat-generation, high light-emitting stability, and long life-span, so that they are widely used in many industrial applications, such as an advertising billboard. The red, green, and blue LEDs are arranged in various shapes of arrays in an advertising billboard to display dynamic images. Because of their high efficiency and stability, LEDs are also widely used to replace conventional small light bulbs as indicators in equipment to display the operating status, such as ON, OFF, PAUSE, or STANDBY, and corresponding options to each status. LEDs are also used to manufacture lighting devices, such as torches, headlights for cars or bicycles. Furthermore, LEDs are also used as light source in communication, such as local-area network (LAN). With light emitted from the LEDS into its end, the multi-mode fiber optical is able to transmit the light inside it for a long distance.
Although the performance of LEDs in aforementioned applications is superior and stable, there exists some obstacles for overcoming. For example, when using red, green and blue LEDs in lighting devices, it is difficult to arrange and mixed the red, green and blue lights to generate the white light that is commonly used in lighting. As the related technology is still under development, the white light generated by current technologies are usually uneven, and sometimes mixed with lights of other colors. Therefore, the overall lighting effect needs improvement.
FIG. 1 shows a structure of a conventional white LED device, comprising a bell-shaped cover 1 made of epoxy for focusing light and protecting the internal components, such as LED 3, from external damages. The power for the LED is fed from the power line, through conducting line supports 4, to the electrodes 5. When the power is on, the LFD emits the light, which is focused and redirected by bell-shaped cover 1, serving as a convex lens. The light then travels straight forwards.
However, the white light generated by the aforementioned technology is usually uneven, and forms a beam that appears yellowish on the side, and bluish at the center. It is because conventional LED device are manufactured by directly applying yellow phosphor on blue LEDs, so that the generated white light is uneven. Furthermore, as the heat generated by the blue LED damages the yellow phosphor, the life span of the device is shortened. These are known disadvantages and restrictions of the convention LED devices.
The inventor of the present invention, based on years of experience and research, provides the present invention to solve the aforementioned obstacles.